Response and acclimation of cyanobacteria to acidification: A comprehensive review.

Cyanobacteria, as vital components of aquatic ecosystems, face increasing challenges due to acidification driven by various anthropogenic and natural factors. Understanding how cyanobacteria adapt and respond to acidification is crucial for predicting their ecological dynamics and potential impacts on ecosystem health. This comprehensive review synthesizes current knowledge on the acclimation mechanisms and responses of cyanobacteria to acidification stress. Detailly, ecological roles of cyanobacteria were firstly briefly concluded, followed by the effects of acidification on aquatic ecosystems and cyanobacteria. Then the review focuses on the physiological, biochemical, and molecular strategies employed by cyanobacteria to cope with acidification stress, highlighting key adaptive mechanisms and their ecological implications. Finally, a summary of strategies to enhance acid resistance in cyanobacteria and future directions was discussed. Utilizing omics data and machine learning technology to build a cyanobacterial acid regulatory network allows for predicting the impact of acidification on cyanobacteria and inferring its broader effects on ecosystems. Additionally, acquiring acid-tolerant chassis cells of cyanobacteria through innovative techniques facilitates the advancement of environmentally friendly production of acidic chemicals. By synthesizing empirical evidence and theoretical frameworks, this review aims to elucidate the complex interplay between cyanobacteria and acidification stressors, providing insights for future research directions and ecosystem management strategies.

Improved salt tolerance of Synechococcus elongatus PCC 7942 by heterologous synthesis of compatible solute ectoine.

Salt stress is one of the essential abiotic stresses for the survival of cyanobacteria. However, the realization of large-scale cultivation of cyanobacteria is inseparable from the utilization of abundant seawater resources. Therefore, research on the regulatory mechanism, as well as the improvement of salt tolerance of cyanobacteria is fundamental. Ectoine, a compatible solute which was found in halophilic microorganisms, has potentiality to confer salt tolerance. Here in this article, the salt tolerance of Synechococcus elongatus PCC 7942 (Syn7942) was significantly improved via expressing the ectoine biosynthetic pathway, reaching an increased final OD750 by 20% under 300 mM NaCl and 80% under 400 mM NaCl than that of wild-type (WT), respectively. Encouragingly, the engineered strain could even survive under 500 mM NaCl which was lethal to WT. In addition, by introducing the ectoine synthetic pathway into the sucrose-deficient strain, the salt tolerance of the obtained strain Syn7942/Δsps-ect was restored to the level of WT under 300 mM NaCl stress, demonstrating that ectoine could substitute for sucrose to combat against salt stress in Syn7942. In order to study the difference in the regulation of mechanism on the salt adaptation process after replacing sucrose with ectoine, transcriptomic analysis was performed for Syn7942/Δsps-ect and WT. The differentially expressed gene analysis successfully identified 19 up-regulated genes and 39 down-regulated genes in Syn7942/Δsps-ect compared with WT under salt stress condition. The results also showed that the global regulation of Syn7942/Δsps-ect and WT had certain differences in the process of salt adaptation, in which Syn7942/Δsps-ect reduced the demand for the intensity of sulfur metabolism in this process. This study provides a valuable reference for further salt tolerance engineering in cyanobacteria.

Engineering a Xylose-Utilizing Synechococcus elongatus UTEX 2973 Chassis for 3-Hydroxypropionic Acid Biosynthesis under Photomixotrophic Conditions.

Photomixotrophic cultivation of cyanobacteria is considered a promising strategy to achieve both high cell density and product accumulation, since cyanobacteria can obtain carbon and energy sources from organic matter in addition to those obtained from CO2 and sunlight. Acetyl coenzyme A (acetyl-CoA) is a key precursor used for the biosynthesis of a wide variety of important value-added chemicals. However, the acetyl-CoA content in cyanobacteria is typically low under photomixotrophic conditions, which limits the productivity of the derived chemicals. In this study, a xylose utilization pathway from Escherichia coli was first engineered into fast-growing Synechococcus elongatus UTEX 2973 (hereafter Synechococcus 2973), enabling the xylose based photomixotrophy. Metabolomics analysis of the engineered strain showed that the utilization of xylose enhanced the carbon flow to the oxidative pentose phosphate (OPP) pathway, along with an increase in the intracellular abundance of metabolites such as fructose-6-phosphate (F6P), fructose-1,6-bisphosphate (FBP), ribose-5-phosphate (R5P), erythrose-4-phosphate (E4P), and glyceraldehyde-3-phosphate (G3P). Then, the native glycolytic pathway was rewired via heterologous phosphoketolase (Pkt) gene expression, combined with phosphofructokinase (Pfk) gene knockout and fructose-1,6-bisphosphatase (Fbp) gene overexpression, to drive more carbon flux from xylose to acetyl-CoA. Finally, a heterologous 3-hydroxypropionic acid (3-HP) biosynthetic pathway was introduced. The results showed that 3-HP biosynthesis was improved by up to approximately 4.1-fold (from 22.5 mg/L to 91.3 mg/L) compared with the engineered strain without a rewired metabolism under photomixotrophic conditions and up to approximately 14-fold compared with the strain under photoautotrophic conditions. Using 3-HP as a "proof-of-molecule", our results demonstrated that this strategy could be applied to improve the intracellular pool of acetyl-CoA for the photomixotrophic production of value-added chemicals that require acetyl-CoA as a precursor in a cyanobacterial chassis.

The prognostic value of TCF1+CD8+T in primary small cell carcinoma of the esophagus.

TCF1+CD8+T cells are reported to exhibit stem-like properties with the ability to self-renew and differentiate into terminal effector T cells (TCF1-CD8+T cells) to enhance antitumor response. Previous studies indicated that TCF1+CD8+ tumor-infiltrating lymphocytes (TILs) are related to response to immunotherapy. However, their role in predicting prognosis for patients with primary small cell carcinoma of the esophagus (PSCCE) remains unclear. In this study, the expression of TCF1+CD8+T was analyzed by multiplex fluorescence immunohistochemistry in tumor tissues of 79 patients with PSCCE. High infiltration of TCF1+CD8+T cells had longer overall survival (OS) than low infiltration (P = .009, hazard ratio [HR] = 0.506). High TCF1+CD8/CD8 ratio (>21%) showed superior OS compared with low ratio (≤21%) (P < .001, HR = 0.394). In the validation set (n = 20), the prognostic value of TCF1+CD8+T cells on OS was also verified. TCF1+CD8+T cells are strong prognostic predictors.

Method for Diagnosis of Acute Lymphoblastic Leukemia Based on ViT-CNN Ensemble Model.

Acute lymphocytic leukemia (ALL) is a deadly cancer that not only affects adults but also accounts for about 25% of childhood cancers. Timely and accurate diagnosis of the cancer is an important premise for effective treatment to improve survival rate. Since the image of leukemic B-lymphoblast cells (cancer cells) under the microscope is very similar in morphology to that of normal B-lymphoid precursors (normal cells), it is difficult to distinguish between cancer cells and normal cells. Therefore, we propose the ViT-CNN ensemble model to classify cancer cells images and normal cells images to assist in the diagnosis of acute lymphoblastic leukemia. The ViT-CNN ensemble model is an ensemble model that combines the vision transformer model and convolutional neural network (CNN) model. The vision transformer model is an image classification model based entirely on the transformer structure, which has completely different feature extraction method from the CNN model. The ViT-CNN ensemble model can extract the features of cells images in two completely different ways to achieve better classification results. In addition, the data set used in this article is an unbalanced data set and has a certain amount of noise, and we propose a difference enhancement-random sampling (DERS) data enhancement method, create a new balanced data set, and use the symmetric cross-entropy loss function to reduce the impact of noise in the data set. The classification accuracy of the ViT-CNN ensemble model on the test set has reached 99.03%, and it is proved through experimental comparison that the effect is better than other models. The proposed method can accurately distinguish between cancer cells and normal cells and can be used as an effective method for computer-aided diagnosis of acute lymphoblastic leukemia.

Prevalence of syphilis infection and associations with sexual risk behaviours among HIV-positive men who have sex with men in Shanghai, China.

The aims of this study were to understand the prevalence and correlates of syphilis infection among HIV-positive men who have sex with men (MSM) in Shanghai, China. A total of 200 HIV-positive MSM participants were recruited using "snowball" sampling. Participants were tested for syphilis and completed a one-time questionnaire which included demographic characteristics, sexual behaviours with male and female sexual partners, substance use, and use of antiretroviral medications. Prevalence of syphilis infection was 16.5%. Among HIV/syphilis co-infected participants, 63.6% reported having anal sex with male partners and 24.2% did not use condoms consistently during the past six months; 66.7% reported having oral sex with male partners and 51.5% reported unprotected oral sex during the past six months. Factors associated with testing seropositive for syphilis infection included receptive anal sex with a male partner in the past six months (AOR = 12.61, 90% CI = 2.38-66.89), illicit drug use in the past six months (AOR = 11.47, 90% CI = 2.47-53.45), and use of antiretroviral medication (AOR = 4.48, 90% CI = 1.43-14.05). These data indicate a need for "positive prevention" interventions targeting HIV-positive MSM in China.

[Investigation of HIV and syphilis infection status and risk sexual behavior among men who have sex with men in four cities of China].

OBJECTIVE: To investigate HIV and treponema pallidum infection status, risky sexual behavior among men who have sex with men (MSM) and its impact factors in China. METHODS: Snowball sampling was used to recruit subjects from April to August in 2008 in Beijing, Harbin, Zhengzhou and Chengdu city. Serological test of HIV and treponema pallidum were conducted and a questionnaire survey was undertaken among subjects. The questionnaire included social demographics, characteristics of sexual partners and sexual behaviors. RESULTS: A total of 1693 subjects was enrolled in present study, which included 1390 MSM/M (82.1%) and 303 MSMW (17.9%). The infection rate of HIV among MSM/M and MSMW subjects were 7.0% (97/1390) and 6.6% (20/303), respectively. The infection rate of treponema pallidum among MSM/M and MSMW subjects were 11.9% (166/1390) and 13.2% (40/303), respectively. The proportions of MSM/M subjects who never used or sometimes used condoms when having same-sex anal intercourse in recent 6 months were 8.6% (120/1390), 45.3% (630/1390), respectively. The according proportions among MSMW subjects were 10.2% (31/303), 44.6% (135/303), respectively. Among MSM/M subjects, the risk factors of risk sexual behaviors included having less than 6 sexual partners (OR = 6.03, 95%CI: 2.54 - 14.28), no same-sex regular sexual partner (OR = 2.18, 95%CI: 1.30 - 3.65), no same-sex casual sexual partner (OR = 2.90, 95%CI: 1.79 - 4.71), T-pattern only during anal intercourse (OR = 1.64, 95%CI: 1.13 - 2.37) or P-pattern only (OR = 1.58, 95%CI: 1.04 - 2.41). Among MSMW subjects, the risk factors of same-sex risk sexual behaviors included having less than 6 sexual partners (OR = 12.95, 95%CI: 2.38 - 70.52), no same-sex regular sexual partners (OR = 0.42, 95%CI: 0.21 - 0.85), never used condom during heterosexual intercourse (OR = 3.53, 95%CI: 1.48 - 8.42). CONCLUSION: The infection rate of HIV and treponema pallidum among MSM subjects were quite high, and the same-sex risk sexual behaviors among MSM subjects were ubiquity, whose risk factors including having less than six of sexual partners, no same-sex casual sexual partner, T-pattern or P-pattern only during anal intercourse and never used condemn during heterosexual intercourse among MSMW subjects no same-sex regular partner was a risk factor in MSMS population, while having same-sex regular partners was a risk factor in MSMW population.